When you first go to a Google sign-on, it asks for your email. Once you input your email, it then shows you the profile picture corresponding to the account, and asks you to input the password. If the account has no profile picture, the icon is blue instead of gray. (Tested in Incognito mode)
That's not correct. If you sign on from an unrecognized computer, it doesn't show your photo. Using incognito mode doesn't make you "unrecognized;" you need to have a different IP.